1. Field of the Disclosure
The present disclosure relates to a relay, and particularly, to a relay which includes a magnet and extinguishes an arc.
2. Background of the Disclosure
Generally, an electronic switching device is a type of electrical contact switching device and may be applied to vehicles, various industrial equipment, machines, etc.
FIG. 1 is a cross-sectional view illustrating a whole structure of a relay. FIG. 2 is a perspective view illustrating a switching unit of a related art relay. FIG. 3 is a plan view illustrating an extinguishment direction of an arc when the relay of FIG. 2 is discharged. FIG. 4 is a plan view illustrating an extinguishment direction of an arc when the relay of FIG. 2 is charged.
As illustrated in FIGS. 1 to 4, the related art relay includes a switching unit S, which switches a circuit, and a driver D that drives the switching unit S.
The switching unit S includes a first fixed contact 10, a second fixed contact 20, a movable contact 30 that electrically connects the first fixed contact 10 to the second fixed contact 20 (hereafter referred to as fixed contacts) or detached the first fixed contact 10 from the second fixed contact 20, and a first magnet 40 and a second magnet 50 (hereinafter referred to as magnets) that respectively include opposite polar surfaces 42 and 52 facing each other with a first contact part C1 and a second contact part C2 (hereinafter referred to as contact parts) therebetween. Here, the movable contact 30 contacts the first fixed contact 10 or is detached from the first fixed contact 10 with respect to the first contact part C1, and the movable contact 30 contacts the second fixed contact 20 or is detached from the second fixed contact 20 with respect to the second contact part C2.
The driver D, for example, is configured with an actuator that generates a driving force with electrical power.
Hereinafter, effects of the related art relay will be described.
When power is applied to the driver D, the movable contact 30 is moved, by the driver D, in a direction (an up direction in FIG. 2) contacting the fixed contacts 10 and 20 and contacts the fixed contacts 10 and 20. When the movable contact 30 contacts the fixed contacts 10 and 20, the circuit is electrically connected to the movable contact 30. When the circuit is connected to the movable contact 30, a current may flow from the first fixed contact 10 to the second fixed contact 20 through the movable contact 30, or flow from the second fixed contact 20 to the first fixed contact 10 through the movable contact 30. For example, in a vehicle, the first fixed contact 10 may be connected to an electricity storage such as a battery of the vehicle, and the second fixed contact 20 may be connected to an apparatus (hereinafter referred to as an electricity consumption-generation apparatus) which consumes and generates electricity like a driver of the vehicle. In this case, when electricity is discharged (hereinafter referred to as discharging of the electricity storage) from the electricity storage to the electricity consumption-generation apparatus, a current applied from the electricity storage to the first fixed contact 10 may be supplied to the electricity consumption-generation apparatus through the movable contact 30 and the second fixed contact 20. On the other hand, when electricity is charged (hereinafter referred to as charging of the electricity storage) from the electricity consumption-generation apparatus into the electricity storage, a current applied from the electricity consumption-generation apparatus to the second fixed contact 20 may be supplied to the electricity storage through the movable contact 30 and the first fixed contact 10.
When the supply of power to the driver D is stopped, the movable contact 30 is moved, by the driver D, in a direction (a down direction in FIG. 2) deviating from the fixed contacts 10 and 20 and is detached from the fixed contacts 10 and 20. When the movable contact 30 is detached from the fixed contacts 10 and 20, the circuit is broken.
In such a process, when the movable contact 30 contacts the fixed contacts 10 and 20 and is detached from the fixed contacts 10 and 20, arcs respectively occur in the contact parts C1 and C2.
As illustrated in FIGS. 3 and 4, the respective arcs occurring in the contact parts C1 and C2 are extinguished by the magnets 40 and 50.
In more detail, the contact parts C1 and C2 are provided within a range of an electric field (an electric field flowing in a down direction in the drawing) which flows from the first magnet 40 to the second magnet 50.
Moreover, when an electricity storage illustrated in FIG. 3 is discharged, a current IC1 at the first contact part C1 flows from the first fixed contact 10 to the movable contact 30 (a direction entering into the paper in the drawing). Also, a current I30 at the movable contact 30 flows from the first contact part C1 to the second contact part C2 (a right direction in the drawing). Also, a current IC2 at the second contact part C2 flows from the movable contact 30 to the second fixed contact 20 (a direction out from the paper in the drawing). Therefore, the arc occurring in the first contact part C1 receives a force F11 in a direction (a left direction in the drawing) based on the Fleming's left hand rule and is moved in an outer direction (the left direction in the drawing) of the first contact part C1. Also, the arc occurring in the second contact part C2 receives a force F21 in a direction (a right direction in the drawing) based on the Fleming's left hand rule and is moved in an outer direction (the right direction in the drawing) of the second contact part C2. The arcs which are respectively moved in the outer directions of the contact parts C1 and C2 are cooled by, for example, an extinguishing material such as air and are extinguished.
On the other hand, when an electricity storage illustrated in FIG. 4 is charged, a current IC2′ at the second contact part C2 flows from the second fixed contact 20 to the movable contact 30 (a direction entering into the paper in the drawing). Also, a current I30′ at the movable contact 30 flows from the second contact part C2 to the first contact part C1 (the left direction in the drawing). Also, a current IC1′ at the first contact part C1 flows from the movable contact 30 to the first fixed contact 10 (a direction out from the paper in the drawing). Therefore, the arc occurring in the first contact part C1 receives a force F11′ in a direction (the right direction in the drawing) based on the Fleming's left hand rule and is moved in an inner direction (the right direction in the drawing) of the first contact part C1. Also, the arc occurring in the second contact part C2 receives a force F21′ in a direction (the left direction in the drawing) based on the Fleming's left hand rule and is moved in an inner direction (the left direction in the drawing) of the second contact part C2. The arcs which are respectively moved in the inner directions of the contact parts C1 and C2 are cooled by, for example, an extinguishing material such as air and are extinguished.
However, in the related art relay, the contact parts C1 and C2 are disposed on a virtual plane which perpendicularly intersects the polar surface 42 of the first magnet 40 and the polar surface 52 of the second magnet 50 (hereinafter referred to as polar surfaces) which face each other. Also, the first contact part C1 is disposed at a position where a distance to the first magnet 40 is the same as a distance to the second magnet 50, and the second contact part C2 is disposed at a position where the distance to the first magnet 40 is the same as the distance to the second magnet 50. In other words, the magnets 40 and 50 are disposed in order for the polar surfaces 42 and 52 to be parallel to a virtual axis A which connects the contact parts C1 and C2. Therefore, the arcs which respectively occur in the contact parts C1 and C2 are moved along the virtual axis A, and when the electricity storage illustrated in FIG. 4 is charged, the arcs gather at centers (a center of the movable contact 30) of the contact parts C1 and C2. Therefore, excessive heat is generated in the centers (the center of the movable contact 30) of the contact parts C1 and C2, and for this reason, the switching unit S (in more detail, the movable contact 30) is damaged.
In the related art relay, the current I30 (I30′) flowing in the movable contact 30 flows in parallel with the polar surfaces 42 and 52 of the magnets 40 and 50. Therefore, a force based on the Fleming's left hand rule is applied to the movable contact 30 by the current I30 (I30′) flowing in the movable contact 30 and a magnetic field B of each of the magnets 40 and 50, and when the electricity storage illustrated in FIG. 3 is discharged, the force is applied in a direction (a direction entering into the paper in the drawing) where the movable contact 30 is detached from the fixed contacts 10 and 20. Therefore, a contacting force between the movable contact 30 and the fixed contacts 10 and 20 is reduced.